This invention relates generally to the field of surgical trocar systems which provide a sealed passageway for insertion and removal of various instruments through a hole in the body wall to reach an internal cavity, where a hollow, tubular cannula maintains an open channel and one or more valves define a seal to close the open channel when no instrument is inserted as well as to seal around an inserted instrument. More particularly, the invention relates to such devices where the trocar assembly is formed of detachable component members, such that the valves are disposable yet the cannula may be sterilized and reused.
Trocar systems are well known in the surgical field. In many procedures, such as laporascopic surgery, access to an internal cavity is achieved by puncturing a relatively small hole through the body wall using a pointed trocar in combination with a tubular cannula, or a sharpened cannula/trocar in combination with an internal obturator. The pointed trocar or obturator is removed from the hollow cannula to open the passageway and typically the internal cavity is distended by introducing a gas into the cavity. A valve seal made of an elastomeric material is used to seal the cannula to prevent escape of the gas from the cavity. Slits or other aperture means in the seal allow an instrument to be inserted through the valve to perform an operation in the internal cavity. Since the instrument must be smaller in outer diameter than the inner diameter of the cannula to allow for insertion and relative movement within the cannula, the seal, or an additional seal, is designed to also prevent gas from escaping through the cannula past the instrument. There are numerous examples of such trocar systems in the art, as well as numerous constructions for the valve seals.
The trocar system of the invention is a multiple component or modular apparatus having at least two detachable or interchangeable main component members or assemblies, one of which consists in general of a cannula, and the other of which consists in general of a passive valve seal assembly and an active instrument or reducer seal assembly. The trocar system provides a gastight seal to prevent passage of gas through the system, with the passive valve seal member comprising means to seal the cannula passageway when no instrument is inserted into the trocar system and the instrument reducer seal member comprising means to seal the passageway in conjunction with an instrument inserted into the cannula.
The cannula comprises an elongated, hollow tube which defines a passageway or axial bore for an instrument and has an open distal end and an expanded mating member on the proximal end, circular in cross-section, for joining the cannula to the valve seal assembly. A pair of opposing cannula detent flanges, each extending approximately 75 degrees around the circumference, are positioned on the exterior of the mating member a short distance from the distal end opening. Each of the cannula flanges is preferably provided with a detent groove or catch member adjacent one end.
The valve seal assembly comprises a housing, generally circular in cross-section and defining and axial bore, having open distal and proximal ends, where the distal end is sized to mate externally with the cannula mating member. The valve seal housing at the proximal end is significantly smaller in diameter than at the distal end, with the two ends joined by a shoulder generally perpendicular to the longitudinal axis. The proximal end mates with the instrument seal assembly and is generally tubular in configuration. The interior wall of the cannula mating portion is generally annular except for the presence of a number of inwardly extending alignment members, oriented in parallel manner in the axial direction, which comprise two opposing pairs of ribs which define the axial pathway for insertion of the cannula mating member into the valve seal housing, the pathway ribs within each set being spaced slightly farther than 65 degrees, the circumferential distance of the cannula ribs, such that the cannula can be inserted in the axial direction into the valve seal assembly with each of the cannula ribs fitting between a pair of the pathway ribs. The interior diameter defined by the innermost surfaces of the pathway ribs is only slightly larger than the exterior diameter of the mating member to create a relatively snug fit between the two components. In each set of pathway ribs, one rib is longer than the other, with one rib extending preferably to the shoulder and extending inwardly from the internal wall sufficient distance to provide a rotation stop against which the cannula ribs abut and cannot pass. The shorter rib extends only about halfway into the valve seal assembly and is capped with a circumferentially extending detent flange. With the cannula inserted within the valve assembly, the pieces can be rotated up to about 90 degrees such that the circumferential cannula ribs pass to the proximal side of the two opposing detent flanges, which prevents axial separation of the two members. Adjacent each of the long ribs defining the insertion pathway is a detent rib or member which extends a shorter distance from the internal wall than the pathway ribs, such that the cannula ribs can be forced past the detent ribs to a point where the detent ribs seat in the detent arooves on the cannula ribs to lock the two members rotationally. Rotation past the detent ribs is stopped by the rotation stop pathway ribs.
The valve seal assembly further comprises seal retention flange members to retain the elastomeric seal within the assembly. A pair of circumferentially extending flange members mounted on the internal wall of the valve seal assembly prevent axial movement of the seal within the assembly, and a pair of curved flange members mounted on the interior of the shoulder prevent radial movement of the seal. The valve seal itself is of the type known as a duckbill seal, having an annular seating member defining a large circular opening, with the seating member having an annular receiving channel on its distal side. A circular wall extends distally from the seating member and transitions into two planar valve members which join along a line intersecting the longitudinal axis and extending across the entire circular wall, where the line contains a slit such that an instrument can be inserted through the valve seal. The valve seal remains closed in the passive state, i.e., where no instrument is inserted to separate the slit and planar valve members. To account for the long pathway ribs and the detent ribs, the annular seating member is provided with two sets of opposing rib slots corresponding in configuration and positioning to the configuration and positioning of the ribs. When the seal is inserted into the passive valve seal assembly, annular seating member abuts the interior of the shoulder and the two pairs of seal retention flanges. When the cannula is inserted into the valve seal assembly, the proximal end of the mating member seats in the annular receiving channel of the seal.
The active instrument or reducer seal assembly mounts onto the proximal end of the valve seal assembly, either in a permanent or releasable manner, or the combination of valve seal assembly and instrument seal assembly is initially formed as an integral member, and comprises a distal mating portion sized to receive the proximal end of the valve seal assembly, a transition shoulder to increase the outer diameter of the instrument seal assembly, an annular wall portion and an end wall perpendicular to the longitudinal axis which has a relatively large circular opening, all operating to define an axial bore. Mounted within the instrument seal assembly is an elastomeric seal having a generally small central aperture, such that the seal forms a gas-tight seal against an instrument when the instrument is inserted through the central aperture. Thus when no instrument is present, the duck bill valve seal prevents gas from passing through the device, but when an instrument is inserted, thereby opening the passive valve seal, the active instrument seal prevents passage of gas by tightly surrounding the instrument. Because the invention is modular, the combined valve seal assembly and instrument seal assembly, or either the valve seal assembly or instrument seal assembly alone if both are detachable, may be discarded and replaced as necessary while the cannula portion can be sterilized and reused.